Magnetostrictive transducers are widely used for distance and liquid level measurements. Magnetostriction is a property of ferromagnetic materials such as iron, nickel, and cobalt. When placed in a magnetic field, these materials change size and/or shape. Distance and liquid level transducers exploit these properties.
Generally, an elongate magnetostrictive waveguide stretched along the length of a transducer's measurement range interacts with the magnetic field of a permanent magnet located at a position to be detected The interaction of a magnetic field from a permanent magnet located at the position to be detected and a magnetic field from short interrogation current pulses passed through the wave guide generate torsional strain waves that propagate from a position to be detected to the pick-up located at one end of the wave guide. The time between an interrogation pulse and arrival of the torsional strain to the pick-up represent a distance. An electronic circuit transmits the interrogation signal through the transducer and senses the torsional strain wave caused by the interaction of the interrogation signal and the magnets. To determine the volume of product in a storage tank, the distance between the horizontal surfaces of the product are determined and the volume is calculated based on the shape of the storage tank and the distances. More than one float can support respective magnets. If the product is less dense than water, water may be found below the product. As the volume of product and the water increase or decrease, the floats move up or down along the magnetostrictive waveguide.
Magnetostrictive materials are effective at generating and transmitting torsional strain waves but exhibit relatively high electrical resistance. A low resistance wire may be used to transmit the interrogation signal. The wire may be inserted in a tubular magnetostrictive wave guide. The length of the transducer and the waveguide is constrained by the internal diameter of the tubular waveguide and the diameter and malleability of the wire. As the diameters decrease, it becomes increasingly more difficult to insert the wire in the tubular waveguide, which limits the practical length of the transducer. On the other hand, if a solid wire wave guide is used to transmit the interrogation signal, additional power is required to overcome the high electrical resistance of the magnetostrictive material. The solid wire approach is less suitable in battery powered systems especially for long transducers.
A need exists for a magnetostrictive transducer that is economical to manufacture and use.
Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of various features and components according to the present disclosure, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention. The exemplification set out herein illustrates embodiments of the disclosure, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.